Schedule II - Condensed Financial Information of Registrant (Parent Company Only) - Condensed Balance Sheet (Parenthetical) (Detail) - USD ($)	Dec. 31, 2015	Dec. 31, 2014	May. 01, 2013	Apr. 30, 2013
Condensed Balance Sheet Statements, Captions [Line Items]
Preferred stock, par value				$ 0.01
Preferred stock, shares authorized				20,000,000
Common stock, par value				$ 0.01
Common stock, shares authorized				130,000,000
Common stock, shares issued				45,000,000
Successor [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Fixed income securities, amortized cost	$ 4,992,756,000	$ 4,514,878,000
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized	130,000,000	130,000,000
Common stock, shares issued	45,044,222	45,005,932	45,000,000
Common stock, shares outstanding	45,044,222	45,005,932
Treasury stock, shares	8,202	2,459
Ambac Financial Group, Inc Parent Company Only [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Fixed income securities, amortized cost	$ 203,709	$ 234,294
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	20,000,000	20,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	130,000,000	130,000,000
Common stock, shares issued	45,044,222	45,005,932
Common stock, shares outstanding	45,044,222	45,005,932
Treasury stock, shares	8,202	2,459